Long pause between shots while shooting brackets on multipule camera rig

I’m capturing HDR brackets ( 9 shots 1 ev ) on a multiple camera rig ( 4x Nikon D850 1x Sony a7r3 ) and there is a undesirable delay between each shot. Not sure if its because it has to process large RAW files or if I’m using the wrong USB cables. I am wondering how to get it to capture without any delay.

When triggering cameras from software (over the USB connection), its not possible to accurately synchronise the timing across multiple cameras. This is because the “trigger” request has to be sent to each camera in sequence. So although the software will attempt to send these trigger requests as quickly as possible, they will always be a small time interval between each camera receiving them.

To try to reduce the time delay, try to disable auto-focus on the cameras, and ensure they are in manual program mode (so they don’t try waste time measuring light levels).

If you need accurate timing, you need to switch to using a dedicated trigger system, that connects to each camera’s external trigger socket.
For example, Esper sell dedicated hardware for this: https://www.esperhq.com/product/multiple-camera-trigger-triggerbox/?ref=145

(apologies for taking so long to answer this)